Fungicidal process employing organic phosphorous acid esters

ABSTRACT

Agricultural and horticultural fungicides of the formula   D R A W I N G

United States Patent Schrader et al.

1 51 Dec.5,1972

[73] Assignee: Nihon Tokusha Noyaku Seizo KabushikiKaisha,Tokyo,Japan[22] Filed: Oct. 20, 1970 21 Appl. No.2 82,528

Related US. Application Data [63] Continuation of Ser. No. 686,278, Nov.28,

19 67, abandoned.

[52] US. Cl ..424/223 3 ,268,393 8/1966 Wilson ..424/325 PrimaryExaminer--Albert T. Meyers Assistant Examiner-Doris J. FunderburkAttorney-Sherman and Shalloway L ABSTRACT Agricultural and horticulturalfungicides of the formula.

wherein R is selected from the group consisting of C1-4 alkyl andchloroethyl, X is selected from the group consisting of chlorineandmethyl and n is zero or one are especially useful for the control of theblast and sheath blight, which have been regarded from the past asserious diseases of rice, processes for the preparation of activeingredients thereof and method of the utilization thereof. Thesefungicides have good control effects and their active ingredientscontain no heavy metals harmful to men and cattle, in contrast to theconventional fungicides heretofore applied for the same purpose whichgive such bad influence as direct and indirect toxicity to men andcattle owing to the presence of heavy metals such as mercury andarsenic.

16 Claims, No Drawings This application is a continuation of applicationSer. No. 686,278 filed Nov. 28, 1967 now abandoned.

The present invention relates to agricultural and horticulturalfungicides whose active ingredients are organic phosphorous acid estersnot containing heavy metals harmful to men and cattle, processes for thepreparation of active ingredients thereof and method of the utilizationthereof.

More particularly, the present invention relates to agricultural andhorticultural fungicides containing a fungicidal amount of at least onecompound selected from the group consisting of organic phosphorous acidesters represented by the following formula l) (wherein R stands for amember selected from the group consisting of alkyl groups and haloalkylgroups, X stands for a member selected from the group consisting ofhalogen atoms and alkyl groups and n is a number selected from the groupconsisting of zero and 1), especially preferably organic phosphorousacid esters of said formula (1') wherein R stands for an alkyl grouphaving one to four carbon atoms, X stands for a member selected from thegroup consisting of chlorine and methyl, and n is a number selected fromthe group consisting of zero and l and organic phosphorous acid CompoundN esters of said formula (1) wherein R stands for C1- CH CH X stands formethyl and n is a number selected from the group consisting of zero andl as active ingredients, processes for the preparation of said activeingredients and method of the utilization thereof.

For the control of blast (Piricuralia oryzae) and sheath blight(Hypochnus sasakii), important diseases of rice from the past, suchcompounds as phenyl mercuric acetate and methyl arsonic acid metalsalts, etc. have been applied extensively due to their superiorfungicidal efficacy and for economical reasons.

Of late, however, the application of organic mercury compounds to riceplant in its growing stage has been brought to light in view of givingbad influence to public health by their direct toxicity and indirectresidual toxicity to the human body. Therefore, the development ofagricultural chemicals not containing these heavy metals harmful to menand cattle and effective against the aforementioned rice diseases andcheap-priced has been earnestly desired.

We, the inventors, after testing biological activity of variousorganicphosphorous acid esters in order to. solve the aforementionedproblem, have discovered that novel organic phosphorous acidesters-shown by the aforementioned general formula 1) were useful asagricultural and horticultural fungicides, though inferior in theirinsecticidal actions, and especially they had excellent efficacy againstimportant rice diseases such as blast, Brown spot '(ti Cochliobolusmiyabeanus) and sheath blight and thus we have completed this invention.

The following Table 1 shows the compounds exemplified to be used in thisinvention.

TABLE 1 Chemical name O-methyl-S,S-di(p-methylphenyl)dithiophosphlte.

0ethyl-S,S-dl(p-methy1phenyl) dithiophosphite.

O-ethyl-S,S-di(p-chlorophenyl) dithiophosphlte.

041- (or i-) propyl-S,S-di(p-methylphenyl) dithiophosphite.

O-n- (or sec-) butyl-S,S-di(p-methylphenyl)dithiophosphite.

O-methyl-S-S-diphenyl dithlophosphite.

Table lContinued Compound No. Structural formula Chemical name 7. S QO-ethyl-S,S-diphenyl dithlophospliito.

C H OP\ 8 s S Q O-n- (oi'i-) propyl-S,S-diplienyl dithiophosphitt'.

v n- (ori) C3H10- '1 O-n- (or 590-) butyl-S S-diphenyl dithiophosphito.

N- (or 500-) clHDO-P 1U Q 0-(2-chloroethyl)-S,S-diphenyldithiophosphite.

S UlCH2CH20-P O-(2-chloroethyl) S,S-di(p-methylphenyl) dithiopliosphite.

The aforementioned compounds may be easily prepared by reacting an alkyldihalogeno phosphorous acid ester represented by the following formula(2) (wherein M stands for a member selected from the group consisting ofhydrogen atom and alkali metal atoms, X stands for a member selectedfrom the group consisting of halogen atoms and alkyl groups and n is anumber selected from the group consisting of zero and l in accordancewith the following reaction scheme:

Said reaction suffices to react a compound of said formula (2) with acompound of said formula (3) in the optional presence of an organicsolvent, however, it is preferable to carry out the reaction withheating.

Of the material dihalogeno phosphorous acid esters of said generalformula (2), a compound wherein R is alkyl is easily synthesized by theknown method using the corresponding alcohol and phosphoroustrichloride. The following are its representative compounds andproperties.

Properties (melting point Chemical name or boiling point) O-methyldichlorophosphorous acid ester m.p. 95 96C. O-ethyl dichlorophosphorousacid ester b.p. 54- 60 C/l00 mm Hg O-propyl dichlorophosphorous acidester m.p. l43 145C O-butyl dichlorophosphorous acid ester b.p. 49".- 50C/l l mm Hg Of the material compounds of said general formula (2), acompound wherein R is haloalkyl may be obtained similarly except using ahalo-substituted alcohol instead of said alcohol.

The representative compound is shown below Chemical nameO'(2-chloroethyl) dichlorophosphorous acid ester ester The reactionshown by said reaction scheme may employ a usually utilized acid-bindingagent such as an organic base, for instance, triethylamine,benzyldimethylamine and pyridine or an inorganic base, for instance,sodium carbonate, potassium carbonate, sodium bicarbonate and potassiumbicarbonate. As a compound of said formula (3), when substituted orunsubstituted thiophenol wherein M is a hydrogen atom is used,utilization of an acid binding-agent is recommended.

As the reaction temperature, normally a temperature within the range of0C. to 80C. may be adopted, however, it is possible to carry out thereaction at a tem- Properties (boiling point.)

b.p. C/5 l0 mm Hg perature higher or lower than said range if desired.

When as a reaction medium an organic solvent is utilized, a solvent, forinstance, hydrocarbon (benzene, xylene, hexane), chlorinated,hydrocarbon, ether and ketone may be utilized.

The reaction time is properly changed depending upon thereaction-temperature, reaction components and other reaction conditions,however, normally a period of l hours is sufficient.

Further, as occasion demands it is possible to carry out the reaction ina nitrogen gas stream.

After completion of the reaction, the product may be obtained byfiltering the produced salts, further washing the filtrate with water oran aqueous solution of carbonic acid and drying with sulfuric sodaanhydride and then removing the solvent, thereafter purifying theproduct as occasion demands.

The compounds of said formula I) obtained by said process are oily orsolid substances generally insoluble in water, but soluble in an organicsolvent, for instance, alcohol, benzene, xylene, hexane, ether, ketone,chlorinated hydrocarbon and hydrocarbon. When they are used, they may beutilized by various methods known in the agricultural and horticulturalfields.

Namely, when the compoundsof this invention are used as agricultural andhorticultural fungicides, they are used diluted'with water directly orin admixture with carriers and formulated into wettable powders,emulsifiable concentrates, dusts, granules or pastes by methodsgenerally used in ordinary agricultural chemicals. As solid carriers areexemplified inactive materials such as talc, clay, kaolin,montmorillonite, diatomaceous earth, calcium carbonate, etc. As liquidcarriers either solvents or even non-solvents which can 6 largeramounts. The used amounts are properly variable depending upon kind ofthe active ingredients, ap-

' plying method, applying period, object of application or formulationof fungicides.

As aforementioned in contrast to the conventional fungicides heretoforeapplied for controlling the most important diseases of rice plant whichhave serious deficiency in that they are directly and indirectly toxicto men and cattle due to containing heavy metals such as mercury andarsenic, the fungicides of this invention completely overcome suchdeficiency due to harmful disperse or dissolve the active ingredient byadjuvant y can be used, e.g., alcohol, benzene, xylene, dimethylnaphthalene, aromatic naphtha, dimethyl formamide, surface active agent,etc.

They can be applied, for assuring their efficacy, in admixture with suchadjuvants used for agricultural chemicals in general as spreader,emulsifier, wetting agent, adhesive agent, etc. Further, they can beapplied in admixture with such insecticides, acaricides and nematocidesas organo-phosphorus compounds, carbonate compounds, chlorinatedcompounds, dinitro compounds, such fungicides as organophosphoruscompounds, organic sulfur, copper compounds, dithiocarbamates, dinitrocompounds, antibiotics, such herbicides as substituted phenoxycompounds, carbamates, urea compounds, triazine compounds, chlorophenol,substituted diphenyl ether, anilide compounds and other agriculturalchemicals and fertilizers.

In using the fungicides of the invention, in case of powder material, itcan be directly dusted on the leaves or stems of plants or treated onthe seed, and in case of emulsifier concentrate, it can be diluted withwater etc. to a suitable concentration and may be applied on leaves andstems of plants by spraying it with a sprayer and in case of wettablepowders they can be applied by spraying as a suspension of a suitableconcentration with water and in case of granular formulation they can besprinkled upon soil as such.

The fungicides of this invention are ordinarily used at a ratio of 25g24 100g, preferably g 100g, especially 60g 80g of the active ingredientsper 10 ares, however, if desired they may be used in smaller or heavymetals, moreover, they have excellent fungicidal effects to ricediseases, above all, blast, Brown spot and sheath spot. As the activeingredient of this invention, a compound wherein R alkyl and n o ispreferable. ln case n is l, a compoundwherein X is alkyl is. moreeffective than a compound wherein X is halogen. N I

The following Examples illustrate the process for the preparation ofactive ingredientsof our invention, but supplements and specificcompounds of the Examples are alterable and will not restrictourinvention. I Examples of preparing the active ingredients:

Example 1 Analysis:

P S Calculated for a molecular weight of 322: 9.6 19.9 Found: 9.1% 20.2

Example 2 CzHsO-P 172 G of p-chlorothiophenol are dissolved in 600 ml ofbenzene. The solution is treated with 124g of triethylamine.Subsequently at 0 to5C there are added g of 0-ethyldichlorophosphorousacid ester while stirring and passing nitrogen through the solution. Thereaction mixture is further stirred for 1 hour and then treated asdescribed in Example 1. There are obtained g (73 percent of thetheoretical) of O- ethyl-S,S-di(p-chlorophenyl)-dithiophosphite in theform of a pale yellow water-insoluble oily matter. Example 3 to 148g (65percent of the theoretical).

Analysis: I P S Cl Calculated for a molecular weight of 377: 8.2% 17.0%

Found: 8.4% 17.2%

Example 4 172 G of p-chlorothiophenol are dissolved in 600 ml ofbenzene. 124 g of triethylamine are added. Then 97g ofO-isopropyldichlorophosphorous acid ester are added to the solution atto 5C with stirring and passing through nitrogen. The reaction mixtureis further stirred for 1 hour andthen treated as described in Example 1.In this way there are obtained 145g (77 percent of the theoretical) ofthe novel O-isopropyl- S,S-di(p-chlorophenyl)-dithiophosphite in theform of colorless needles.

Analysis:

Calculated for a molecular weight of 377 8.2%

' 18.8% Found: 8.4% 17.3%

Example 5 The mixed solution of 22g of thiophenol, 20g of triethylamineand 100 ml of benzene is added dropwise into a solution wherein 14.7g ofO-ethyldichloro phosphorous acid ester are dissolved in 200 ml ofbenzene at 10 15C. After the completion of dropping, stirring is furthercontinued for 3 hours at 10C and the formed amine salt is filtered. Thefiltrate is washed with water and 1 percent sodium carbonate aqueoussolution twice and dried with sulfuric soda anhydride. When the benzeneis distilled off and dried under a reduced pressure (0.05 mm Hg) at100C. 26.5g of light yellow and oily O-ethyl-S,S-diphenyldithiophosphite are obtained.

Example 6 205 G of triethylamine are added into a solution wherein 220gof thiophenol are dissolvedin 1,000 ml of benzene. Into this solutionthe solution of 100 ml of benzene in which 150g of O-ethyldichlorophosphorous acid ester are dissolved is added dropwise at 0 5C.gradually with stirring. After the reaction mixture is stirred for 2hours more at the room temperature, it-is washed with ice water and thebenzene solution is separated. After the organic layer is dried oversulfuric soda anhydride and the solvent is distilled off under a reducedpressure, 265g percent of theoretical value) of light yellow,water-insoluble and oily O-ethyl- S,S-diphenyl dithiophosphite areobtained, boiling at 134C. (0.01 mm Hg) Example 7 13.2 G of sodium saltof thiophenol are added into 200 'ml of methyl ethyl ketone. Into thissolution, 7.3g of (ii-ethyl. dichloro phosphorous acid ester are addeddropwise with stirring. After continuing the stirring for eight hours at60C, the formed inorganic salt is filtered. Methyl ethyl ketone isdistilled off and the residue is dissolved in ether. After being washedwith a 1 percent sodium carbonate aqueous solution and water, ethersolution is dried over sodium sulfate anhydride and ether is distilledoff. Then 11.5g of O- ethyl-S,S-diphenyl dithiophosphite are obtained.Example 8 8 G of O-n-propyl dichloro phosphorous acid ester are addeddropwise into a solution wherein 11g of thiophenol and 10g of triethylamine are dissolved in 200 ml of benzene at room temperature.

After having stirred for an hour, the mixture is refluxed for 2 hours.After cooling, aminesalt is filtered and further treated as described inExample 1. Under the reduced pressure (0.05 mm Hg) at C. 13.5g ofundistillable oily O-n-propyl-S,S-diphenyl dithiophosphite are obtained.

Example 9 .124 G of triethyl amine are added into a solution wherein132g of thiophenol are dissolved in 600 ml of benzene. To this solution7g of O-n-propyl dichloro phosphorous acid esters are added at 0 5C withstirring and passing through nitrogen gas. After the reaction mixture isstirred for an hour, it is washed with water until it reacts neutrality.Then the benzene solution is dried over sulfuric soda anhydrideand thesolvent is distilled off. Then 147g (80 percent of theoretical value) oflight yellow, water-insoluble and oily O-npropyl-S,S-diphenyldithiophosphite are obtained.

Analysis: P S Calculated for a molecular weight of 322: 10.1% 20.8%Found: 9.6% 21.0%

U 124 G' of triethyl amine are added into a solution wherein 132g ofthiophenol are dissolved in 600 ml of benzene. Into this solution 97 gof O -isopropyl phosphorous acid ester are added dropwise at 5C withstirring. Further having stirred for an hour, the reaction mixture istreated in the'manner as described in Example l and then 150g (81percent of theoretical value) of yellow, water-insoluble and oilyO-iso-propyl- S,S-diphenyl dithiophosphite boiling at l l8C/0.0l mm Hgare obtained. Example 1 l C1'C2H40-P A mixed solution of 22g ofthiophenol, 20g of triethyl amine and 100 ml of benzene is addeddropwise into solution wherein l8.lg of O-(2-chloroethyl)dichlorodichloro phosphorous acid ester are dissolved in 200 ml ofbenzene at 10-C.

After the completion of dropping, stirring is further continued for 3hours at C and the formed amine salt is filtered. The filtrate istreated in the manner as described in Example 1 and then 24.7g of lightyellow and oily O-(2-chloroethyl)-S,S-diphenyl dithiophosphite areobtained.

The following Examples illustrate the preparation of fungicides and alsothe method of using the same will be explained in the followingexamples. v

It should be noted that the additives and active ingredients may bechanged over a wide range.

[ ll Preparation of fungicides (compositions) Example 1 1 50 Parts ofO-ethyl-S,S-di(p-methylphenyl) dithiophosphite, 48 parts of clay and 2parts of emulsifier Sorpol W-l50 (active ingredient polyoxyethylenealkylarylether, Toho Kagaku Kogyo K.K., Japan) are formulated into awettable powder by crushing and mixing and applied diluted with water.In case of using, the wettable powder was suspended in water and sprayedon the leaves and stems of paddy field rice plant infected by rice blast(Piricularia oryzae) to destroy the disease. Example2 3 Parts ofO-ethyl-S,S-di(p-chlorophenyl) dithiophosphite and 97 parts of mixtureof talc and clay are formulated into a dust by crushing and mixing andapplied as it is. Example 3 Parts of O-ethyl-S,S-diphenyldithiophosphite, 25 parts of O-ethyl O-cyclohexyl S-(p-chlorophenyl)thiophosphate, parts of xylene and 20 parts of emulsifier Sorpol 2020(active ingredient polyoxyethylene alkylarylether, Toho Kagaku KogyoK.K., Japan) are formulated into an emulsifiable concentrate by mixingand stirring and applied diluted with water. Example 4 50 Parts ofO-propyl-S,S-diphenyl dithiophosphite, 48 parts of clay, 2 parts ofemulsifier Sorpol W -l50 (trade name of the product of Toho Kagaku KogyoK.K., Japan) are formulated into a wettable powder by crushing andmixing and applied diluted with water. Example 5 v 30 Parts ofO-ethyl-S,S-diphenyl dithiophosphite, 50

1 parts of xylene and 20 parts of emulsifier Sorpol-2020 centrate bymixing and stirring and applied diluted with water.

Example 6 2 Parts of O-ethyl- S,S-diphenyl dithiophosphite, 2 parts ofQ,O-dimethyl' O-(4-methylthio-m-tolyl) phosphorothioate and 96 parts ofmixture of talc and clay. are formulated into dust by crushing andmixing and applied as it is. The powder may be directly dusted by meansof a duster on the spots where rice blast Piricularia oryzae),- sheathblight (Pellicularia sasakii) or rice stem borer have been infected todestroy the disease. Example 7 50 Parts ofO-(2-chloroethyl)-S,S-di(p-methylphenyl) dithiophosphite, 30 parts ofxylene and 20 partsof emulsifier Sorpol 2020 (trade name of the productof Toho Kagaku Kogyo K.K., Japan) are formulated into an emulsifiableconcentrate by mixing and stirring, and

applied after diluted with water.

Example 8 2 Parts of O-( 2-chloroethyl)-S,S-diphenyldithioph0s phite and98 parts of-mixture of talc and clay are formulated into a dust bycrushing and mixing, and applied as it is.

Example 9 i A solution of 5 parts of O-ethyl-S,S-diphenyldithiophosphite in a solvent is sprayed over parts of vermiculite 'to'form a granular preparation, and is sprinkled over soil as such.

[III Applying Example:

Some experimental results of fungicidal effect of the compounds of thepresent invention are shown in the following Tables II, III. Testingmethods:

a. Tests against blast (Pot test) i Paddy rice (Jukkoku variety)was-cultivated in pots with the diameters of 12 cm and the suspensionsof test chemicals were sprayed on rice plants at their young ear formingperiod. From the next day the treated rice plants were kept in a greenhouse at a temperature of 25C for 48 hours. During that time thesuspensions of spores of rice blast pathogen were sprayed forinoculation twice. After the inoculated rice plants were kept in thegreen house for 7 days, the disease attack rates per pot were classifiedin the degrees from 0 (no attack) to 5 (heavy attack) and valued. Thecontrolling values of the testing chemicals were calculated out by theindex numbers obtained from the disease attack rates to paddy rice inthe treated plots against those inthe control plots. f

b. Tests against sheath blight (Pot test) The suspensions of testchemicals were applied to paddy rice seedlings (Kinmaze variety)cultivated in pots with the diameters of 12 cm for 14 days after theirsowing, and then the suspension of spores of sheath blight germscultured on the barley medium for 10 days was sprayed for inoculation atthe part close to the earth. They were kept at high temperature andhumidi- V ty for 5 days for accelerating disease attack. As in the caseof blast, the disease attack rate per pot was classified in degrees from(no attack) to (heavy attack) and valued. Then the controlling values oftest compounds were calculated and compared. c. Test against plantpathogen (agar dilution method) The compounds of this invention weremixed in the agar culture medium of potato making the concentration asprescribed. After the agar was poured into schales with the diameters of9 cm and hardened, pathogen was inoculated. After having been culturedat 27C for 4 days, the growth condition of pathogen was investigated andthe lowest concentration of growth inhibition was sought.

methyl, and n is zero or 1, said phosphorous acid ester TABLE IIConcentra- Blast Sheath blight tion of act. ing Rate of Controlling.Rate of Controllim. (p.p.m attack value attack value Compounds No.:

1 200 '2. 0 60 2. 0 U0 500 1. 0 80 U. 3 J1 y 200 1. e or 3. 0 40 l 5000. 8 8r! 0. 5 J0 3 I 200 2. U 60 3.0 'l 500 1. 2 76 1. 5 70 4 200 2. 256 3. U 500 2. 0 60 1. 5 70 5 200 2. 5 so a. o 40 l 500 1.5 70 1.15 61 6t 200 2. 5 l. 8 64 'l 500 0.5 10 0.5 )0 200 U. 5 JO 2. 5 50 I 500 0 1000. 3 U4 8 5 200 0. a s4 2. a 4: l .500 0. 5 90 1. 2 T6 t 200 2. 2 56 3.5 3o l 500 1.2 70 1. 8 (A m t 200 1. 0 s0 3. 0 40 'l 500 0 100 .2. U 6011 i 200 2. 5 50 3. 5 'l 500 1. 5 70 2. 0 it Kitazin (marketedgood-comparison lhenyl mercuric acetate (marketed good-comparison)....-12 0.6 as Urbazide (comparison) so 0. 8 84 Non-treatment 5. o 0 5. 0 0

TAB LE III Concentration oi pathogen growth inhibition by agar dilutionmethod (p.p.m.

Alternaria Myco- Piricularia kikuchz'anu spliacrcllu org/earCuchlioboluc I'Iypuclmus Tanuka mclonis I-usarium Compounds No. C'at'aramiyabcanus sasakii (pear) (cucumber) orysporz'um 10 25 100 100 50 100 1?5(5) 1% 100 100 100 1 "J 50 50 50 It) 25 50 100 100 100 25 100 100 200100 100 Nora:

1. The numbers of compounds in the Tables II. 111 are the same as thoseof the aforementioned compounds exemplified in Table I. 2. Kitazin:0,0-diethyl-S-benzylphosphorothiolate. 3. Urbazide:Methylarsin-bisdimethyldithiocarbamate.

What is claimed is:

1. A process for controlling blast (Piricuralia oryzae). brown spotCochliobolus miyabeanus) and sheath blight (Hypochnus sasakii of riceplants which comprises applying to a rice plant, rice seed or soil aneffective amount of an agricultural and horticultural fungicidecomposition consisting essentially of an agriculturally andhorticulturally acceptable carrier and an organic phosphorous acid esterof the formula:

wherein R represents a member selected from the group consisting ofalkyl of from one to four carbon atoms and a chloroethyl group, Xrepresents a member selected from the group consisting of chlorine andchloroethyl)-S,S-diphenyl dithiophosphite.

8. The process of claim 1 wherein the ester is 0-(2-chloroethyl)-S,S-di( p-methylphenyl) dithiophosphite.

9. The process of claim 1 wherein the ester isO-npropyl-S,S-di(p-methylphenyl) dithiophosphite.

10. The process of claim 1 wherein the ester isO-nbutyl-S,S-di(p-methylphenyl) dithiophosphite.

11. The process of claim 1 wherein the ester is O-npropyl-S,S-diphenyldithiophosphite.

12. The process of claim 1 wherein the ester is O-nbutyl-S,S-diphenyldithiophosphite.

13. The process of claim 1 wherein the ester isO-ipropyl-S,S-di(p-methylphenyl) dithiophosphite.

14. The process of claim 1 wherein the ester is O-sec.-butyl-S,S-di(p-methylphenyl) dithiophosphite.

15. The process of claim 1 wherein the ester is O-ipropyl-S,S-diphenyldithiophosphite.

16. The process of claim 1 wherein the ester is Osec.-butyl-S,S-diphenyl dithiophosphite.

2. The process of claim 1 wherein the ester isO-methyl-S,S-di(p-methylphenyl) dithiophosphite.
 3. The process of claim1 wherein the ester is O-ethyl-S,S-di(p-methylphenyl) dithiophosphite.4. The process of claim 1 wherein the ester is O-ethyl-S,S-di(p-chlorophenyl) dithiophosphite.
 5. The process of claim 1wherein the ester is O-methyl-S,S-diphenyl dithiophosphite.
 6. Theprocess of claim 1 wherein the ester is O-ethyl-S,S-diphenyldithiophosphite.
 7. The Process of claim 1 wherein the ester isO-(2-chloroethyl)-S,S-diphenyl dithiophosphite.
 8. The process of claim1 wherein the ester is O-(2-chloroethyl)-S,S-di(p-methylphenyl)dithiophosphite.
 9. The process of claim 1 wherein the ester isO-n-propyl-S,S-di(p-methylphenyl) dithiophosphite.
 10. The process ofclaim 1 wherein the ester is O-n-butyl-S,S-di(p-methylphenyl)dithiophosphite.
 11. The process of claim 1 wherein the ester isO-n-propyl-S,S-diphenyl dithiophosphite.
 12. The process of claim 1wherein the ester is O-n-butyl-S,S-diphenyl dithiophosphite.
 13. Theprocess of claim 1 wherein the ester isO-i-propyl-S,S-di(p-methylphenyl) dithiophosphite.
 14. The process ofclaim 1 wherein the ester is O-sec.-butyl-S, S-di(p-methylphenyl)dithiophosphite.
 15. The process of claim 1 wherein the ester isO-i-propyl-S,S-diphenyl dithiophosphite.
 16. The process of claim 1wherein the ester is O-sec.-butyl-S, S-diphenyl dithiophosphite.